The present invention relates to an image forming apparatus in which a printing member for printing figures, characters, etc. is reciprocated in a predetermined direction to form an image on a recording sheet.
There is known, as one of output devices of computers and workstations, an image forming apparatus employing an ink-jet system in which ink is ejected to form an image on a recording sheet. The image forming apparatus employing an ink-jet system comprises, for example, a print head having a plurality of ink ejection outlets each for ejecting ink, a carriage on which the print head is mounted, said carriage reciprocating in a predetermined direction, and a conveying device for intermittently conveying recording sheets in a direction (a recording sheet conveying direction) intersecting perpendicularly to the predetermined direction.
In the event that an image is recorded on a recording sheet, the recording sheet in the course of conveyance by the conveying device is temporarily stopped, and while the carriage is reciprocated in the predetermined direction, ink is ejected from the ink ejection outlets in accordance with a control of the print head to form (print) a band of image on a portion located at an image formation area of the recording sheet. Thereafter, the recording sheet is fed by a predetermined length to form an image on a new portion located at the image formation area, of the recording sheet. Such a performance is repeated.
The conveying device comprises, usually, a drive roller having a drive roller axle extending in a direction intersecting perpendicularly to the recording sheet conveying direction, and a plurality of driven rollers each detachably mounted on the drive roller for pressing the outer peripheral surface of the drive roller. The drive roller and the driven rollers support a recording sheet in cooperation with one another and convey the recording sheet to the image formation area in such a manner that the recording sheet is sticked on the outer peripheral surface of the drive roller.
In the course of conveyance of the recording sheet in this manner, it happens that a jam occurs for example, around the drive roller. In case of the occurrence of the jam, there is a need to remove the recording sheet by separating the driven rollers from the drive roller. It happens, however, that a movable distance of the driven rollers for separation from the drive roller is too short to access the place at which the jam has occurred. Further, even if it is accessible, it happens that the recording sheet is broken because of insufficient grasp for the recording sheet. Consequently, in some cases, it would take a long time to solve the jam.
After solving the jam, the drive roller is pressed by the driven rollers and the recording sheet is conveyed while supported by the drive roller and the driven rollers. In this case, it happens that the driven rollers are out of their regular positions. In such a case, it happens that rotating the drive roller in some turns causes the driven rollers to take to the drive roller so that the driven rollers are regulated in their positions. However, in this case, it happens that the recording sheet is not conveyed in a proper conveyance direction during a period of time until the driven rollers have been regulated in their positions. Thus, there is a possibility that the jam again occurs.
Further, when the jam occurs, it happens that the carriage stops upward the driven rollers. In such a situation, when the driven rollers are separated from the drive roller so as to remove the recording sheet, there is a possibility that the driven rollers collide with the carriage or the print head which is mounted on the carriage, and as a result they are damaged.
In view of the foregoing, it is an object of the present invention is to provide an image forming apparatus capable of readily removing, when a jam occurs, a recording sheet which undergoes the jam.
The present invention has been made to attain the above-mentioned object and is to provide a first image forming apparatus in which a recording sheet is conveyed in a predetermined recording sheet conveyance direction, and an image is formed on a portion of the conveying recording sheet, said portion being located at an image forming area for forming images, said image forming apparatus comprising:
(1) a drive roller, having a drive roller axle extending in a direction intersecting said predetermined recording sheet conveyance direction, for rotating on said drive roller axle to convey recording sheets to said image forming area;
(2) a first shaft rotatably fixed on a main frame of the apparatus, extending in parallel to said drive roller axle at a position apart from said drive roller;
(3) a driven roller for supporting and conveying a recording sheet between said drive roller and said driven roller by pressing an outer peripheral surface of said drive roller, said driven roller being separated from the outer peripheral surface by rotating on said first shaft in cooperation with a rotation of said first shaft;
(4) a discharge roller, having a discharge roller axle extending in a direction intersecting said predetermined recording sheet conveyance direction, for rotating on said discharge roller axle to discharge recording sheets, said discharge roller being arranged at downward stream end with respect to the recording sheet conveyance direction as compared with said image forming area;
(5) a second shaft rotatably fixed on the main frame of the apparatus, extending in parallel to said discharge roller axle at a position apart from said discharge roller;
(6) a driven discharge roller for supporting and discharging a recording sheet between said driven discharge roller and said discharge roller by pressing an outer peripheral surface of said discharge roller, said driven roller being separated from the outer peripheral surface by rotating on said second shaft in cooperation with a rotation of said second shaft; and
(7) a control lever rotatable in a predetermined direction for rotating both said first and second shafts in cooperation with a rotation of said control lever in the predetermined direction,
wherein said driven roller comprises:
a first driven roller for pressing the outer peripheral surface of said drive roller; and
a second driven roller for pressing a surface, of the outer peripheral surface of said drive roller, which surface is different from a surface, of the outer peripheral surface of said drive roller, pressed by said first driven roller, and
wherein said image forming apparatus further comprising:
a first lever of which the tip portion said first driven roller is rotatably fixed on, said first lever being rotatable on its rear portion in a first detachable direction in which said first driven roller is attachable and detachable to and from the outer peripheral surface of said drive roller; and
a second lever of which the center portion said second driven roller is rotatably fixed on, the tip portion of said second lever being located in the vicinity of said first lever, said second lever being rotatable on its rear portion in a second detachable direction in which said second driven roller is attachable and detachable to and from the outer peripheral surface of said drive roller,
wherein said second lever is rotated so as to separate said second driven roller from the outer peripheral surface of said drive roller through pressing the tip portion of said second lever by said first lever when said first lever rotates so that said first driven roller separates from the outer peripheral surface of said drive roller.
In the image forming apparatus as mentioned above, said driven roller comprises:
(8) a first driven roller for pressing the outer peripheral surface of said drive roller within a range between two straight lines which incline by 45xc2x0 to a rotational direction of said drive roller and a reverse direction opposite to the rotational direction, respectively, with respect to a Y axis perpendicularly intersecting said drive roller axle; and a second driven roller for pressing the outer peripheral surface of said drive roller within a range between two straight lines which incline by 45xc2x0 to the rotational direction of said drive roller and the reverse direction opposite to the rotational direction, respectively, with respect to an X axis perpendicularly intersecting said drive roller axle and the Y axis, (9) wherein said image forming apparatus further comprises:
a first lever extending along the X axis, said first lever being rotatable in a first detachable direction in which said first driven roller is attachable and detachable to and from the outer peripheral surface of said drive roller, wherein said first driven roller is rotatably fixed on said first lever; and a second lever extending along the Y axis, said second lever being rotatable in a second detachable direction in which said second driven roller is attachable and detachable to and from the outer peripheral surface of said drive roller, wherein said second driven roller is rotatably fixed on said second lever, and
(10) wherein it is acceptable that said first shaft comprises:
a first lever shaft for rotatably fixing said first lever in the first detachable direction; and a second lever shaft for rotatably fixing said second lever in the second detachable direction.
Further, it is acceptable that
(11) said first lever rotates in the first detachable direction in cooperation with a rotation of said control lever, and
(12) said second lever rotates in the second detachable direction in cooperation with a rotation of said first lever.
Furthermore, it is acceptable that
(13) said second shaft is disposed at a downward stream end with respect to the recording sheet conveyance direction as compared with said driven discharge roller.
In order to accomplish the above-mentioned object, there is provided a second image forming apparatus having recording sheet conveyance means for conveying recording sheets to an image forming area for forming images, wherein an image is formed on a recording sheet conveyed by said recording sheet conveyance means to the image forming area,
said recording sheet conveyance means comprises:
(14) a drive roller rotatable on a drive roller axle extending in a direction intersecting a recording sheet conveyance direction;
(15) a first lever extending along an X axis perpendicularly intersecting said drive roller axle, said first lever being rotatable on a first lever shaft separated from said drive roller in such a manner that said first lever is attachable and detachable to and from an outer peripheral surface of said drive roller;
(16) a second lever extending along a Y axis perpendicularly intersecting both said drive roller axle and said X axis, said second lever being rotatable on a second lever shaft separated from said drive roller in such a manner that said second lever is attachable and detachable to and from the outer peripheral surface of said drive roller;
(17) a first driven roller rotatably fixed on said first lever, said first driven roller supporting the recording sheet between it and said drive roller through pressing the outer peripheral surface of said drive roller when said first lever is in contact with the outer peripheral surface of said drive roller, and said first driven roller separating from the outer peripheral surface of said drive roller when said first lever separates from the outer peripheral surface of said drive roller; and
(18) a second driven roller rotatably fixed on said second lever, said second driven roller supporting the recording sheet between it and said drive roller through pressing the outer peripheral surface of said drive roller when said second lever is in contact with the outer peripheral surface of said drive roller, and said second driven roller separating from the outer peripheral surface of said drive roller when said second lever separates from the outer peripheral surface of said drive roller,
(19) wherein said first lever has a slide cam shaft penetrating in a direction intersecting a rotational direction of the first lever at a position separating from said first lever shaft; and
(20) said second lever has a slide cam for separating said first lever from said drive roller through pushing said slide cam shaft when said second lever separates from the outer peripheral surface of said drive roller, and
(21) wherein it is acceptable that said image forming apparatus comprises a control lever for rotating said second lever by rotating itself in a predetermined direction, and that said first lever is rotated so as to separate said first driven roller from the outer peripheral surface of said drive roller through pressing the first lever by said second lever when said second lever rotates so that said second driven roller separates from the outer peripheral surface of said drive roller.
(22) Further, it is acceptable that said slide cam shaft separates from said slide cam, when said first and second driven rollers press the outer peripheral surface of said drive roller.
In order to accomplish the above-mentioned object, there is provided a third image forming apparatus having a print member for forming an image on a recording sheet while reciprocating in a predetermined direction, and a plurality of sets of pair of conveyance rollers for supporting and conveying recording sheets in a direction intersecting said predetermined direction, wherein said plurality of sets of pair of conveyance rollers are used to convey a recording sheet to an image forming area for an image formation within a range of a reciprocation of said print member, and an image is formed on the recording sheet by said print member, said image forming apparatus comprises:
(23) a separating member for separating said pair of conveyance rollers from one another;
(24) a control lever for controlling said separating member through rotating in a predetermined rotational direction so that said pair of conveyance rollers are separated from one another; and
(25) a changeover element for permitting said control lever to rotate when said print member moves in the predetermined direction and is not located at an interference area in which said print member collides with the conveyance rollers separated by said separating member, and for prohibiting said control lever from rotating when said print member is located at the interference area.
In the image forming apparatus as mentioned above,
(26) it is acceptable that the apparatus further comprises a rotary cam rotatable together with said control lever,
(27) wherein said changeover element permits said control lever to rotate by separating from said rotary cam when said print member is located at a home position away from said image forming area, and for prohibiting said control lever from rotating by being in contact with said rotary cam.
Further, in the image forming apparatus as mentioned above,
(28) it is acceptable that the apparatus further comprises a control lever shaft rotatable together with said control lever, and
(29) a lever shaft on which said rotary cam is fixed, said lever shaft being coupled with said control lever shaft and rotatable together with said control lever shaft.